For sustainable packaging, many of our customers use Green Packaging Group!
Every time I'm asked about this, I always say that e-commerce and logistics have a huge carbon footprint associated. Our first goal should be to reduce the carbon footprint as much as possible, which sounds like is the aim of this thread so that's fantastic! However, for all other actions that can't be mitigated, it's helpful to offset. One of the best solutions I've found for this is EcoCart's Shopify app, which enables customers to make their orders carbon neutral by checking a box at checkout, which funds certified carbon offset projects like planting trees or building wind farms. https://apps.shopify.com/ecocart
I came across these folks, it looks like mainly packaging but perhaps worth a call? Based on how they are positioned in the article below, I think they are in India. I can't vouch for them, it was just a Google search. https://www.corugami.com/
I also came across this article. Maybe they have more info on labels/hang tags. https://www.ethicoindia.com/a-comprehensive-guide-to-sustainable-packaging/
On https://thriftcollective.com we have been using Ecoenclose for months and they are excellent.
We also found a rubber stamp with binding ink so we can customize our packaging with our logo by stamping bags.